1. Field of the Invention
A communication terminal having a communication function such as a facsimile transmission function.
2. Description of the Related Art
The ITU-T Recommendation T.38 was established in 1999 for conducting T.30 packet signal communication in real time between facsimile terminals over a packet network. The ITU-T Recommendation T.38 provides two advantages at the same time, namely, function exchange and real time communication between facsimile terminals via a public switched network and little cost in communicating over a network.
After the ITU-T Recommendation T.38 was established, a technology, such as in Japanese Laid-Open Patent Application No. 2002-111952, has been proposed for enabling real-time communications between a network terminal apparatus conforming to the ITU-T Recommendation T.38 and a conventional type facsimile terminal.
Japanese Laid-Open Patent Application No. 2002-111952 discloses a network facsimile terminal that can perform facsimile transmission even when the facsimile terminal of the opponent is not a network facsimile terminal that is directly connectable to a packet network. More specifically, the disclosed network facsimile terminal adjusts the waiting time for receiving and transmitting a signal to the opponent in accordance with the type of the opponent's facsimile terminal. For example, in a case where the opponent's facsimile terminal is a network facsimile terminal that conforms to the ITU-T Recommendation T.38 and is directly connectable to a packet network, the disclosed network facsimile terminal sets a first waiting time. In a case where the opponent's facsimile terminal is a facsimile terminal that does not conform to the ITU-T Recommendation T.38, the disclosed network facsimile terminal sets a second waiting time which is longer than the first waiting time.
The network terminal conforming to the ITU-T Recommendation T.38 (hereinafter referred to as “T.38 terminal”) includes an IAF (Internet Aware Fax) type network terminal that is directly connectable to a network and a GW (GateWay) type network terminal that transfers data signals over a telephone network (e.g. public switched telephone network, private line network) in real time.
In a case of communicating in a TCP (Transmission Control Protocol) mode conforming to the ITU-T Recommendation T.38, the communication can be achieved at a high speed.
However, in a case where the receiving side is a GW type T.38 terminal connected to a G3 FAX, the G3 FAX of the receiving side is to perform communications at a speed negotiated (handshake) according to the ITU-T Recommendation T.30. From the standpoint of a terminal on the sending side (e.g. IAF type terminal), this causes the amount of communication data that can be processed in a single time unit (i.e. communication throughput) to decrease.